Rep. Zoe Lofgren, a Democrat whose district includes part of the San Francisco Bay Area, in 2009
U.S. House of Representatives

The FBI and other police agencies would be required to obtain search warrants before reading Americans' e-mail or tracking their mobile devices under a bill introduced in the U.S. House of Representatives today.

It's not a new proposal: Rep. Zoe Lofgren, a Democrat whose district includes the heart of Silicon Valley, announced almost exactly the same measure last fall. But because the clock ran out without Congress acting, she's trying a second time.

"Fourth Amendment protections don't stop at the Internet," Lofgren said in a statement today. "Americans expect Constitutional protections to extend to their online communications and location data."

Last year's version had zero co-sponsors, making it more of a symbolic measure than something designed to move quickly through a GOP-dominated House. This time, Lofgren's bill (PDF) has two other sponsors, including a Republican, Ted Poe of Texas.

When it comes to recognizing that Americans' privacy rights will be recognized in an era of cloud computing, the House has lagged behind the Senate. Last November, the Senate Judiciary committee approved a measure that would curb law enforcement's warrantless access to the contents of e-mail, private Facebook posts, and other data that Americans store in the cloud.

Lofgren's bill would amend the 1986 Electronic Communications Privacy Act, enacted during the pre-Internet era of telephone modems, dial-up bulletin boards, and 5.25-inch floppy disks. ECPA is so convoluted that it's difficult even for judges to follow, and was hardly written with cloud computing and social networks in mind.

ECPA reform is backed by a phalanx of companies, including Amazon.com, Apple, AT&T, eBay, Google, Intel, Microsoft, and Twitter, as well as liberal, conservative, and libertarian advocacy groups. They hope to simplify ECPA's wording while requiring police to obtain a search warrant to access private communications and the locations of mobile devices -- a requirement that doesn't always apply today. (Under current law, Internet users enjoy more privacy rights if they store data locally, a counterintuitive legal hiccup that could slow the shift to cloud-based services unless it's changed.)

But it's easier to block legislation than advance it. The U.S. Department of Justice has previously warned that requiring warrants for e-mail could have an "adverse impact" on investigations. And tougher legal standards for location data, the department claims, would hinder "the government's ability to obtain important information in investigations of serious crimes." Local and state law enforcement groups have also raised concerns.